The embodiments described herein relate generally to medical devices for therapeutic electrical energy delivery, and particularly to systems and methods of high voltage electrical energy delivery in the context of ablating tissue rapidly and selectively by the application of pulsed voltage waveforms to produce exogenous electric fields to cause irreversible electroporation of tissue with the aid of suitably positioned catheter devices with multiple electrodes.
In the past two decades, the technique of electroporation has advanced from the laboratory to clinical applications, while the effects of brief pulses of high voltages and large electric fields on tissue has been investigated for the past forty years or more. Application of brief, high DC voltages to tissue, thereby generating locally high electric fields typically in the range of hundreds of Volts/centimeter, can disrupt cell membranes by generating pores in the cell membrane. While the precise mechanism of this electrically-driven pore generation (or electroporation) is not well understood, it is thought that the application of relatively large electric fields generates instabilities in the lipid bilayers in cell membranes, causing the occurrence of a distribution of local gaps or pores in the membrane. If the applied electric field at the membrane is larger than a threshold value, the electroporation is irreversible and the pores remain open, permitting exchange of material across the membrane and leading to necrosis and/or apoptosis (cell death). Subsequently the tissue heals in a natural process.
Some known processes of adipose tissue reduction by freezing, also known as cryogenically induced lipolysis, can involve a significant length of therapy time. In contrast, the action of irreversible electroporation can be much more rapid. Some known tissue ablation methods employing irreversible electroporation, however, involve destroying a significant mass of tissue, and one concern is the temperature increase in the tissue resulting from this ablation process.
While pulsed DC voltages are known to drive electroporation under the right circumstances, known approach do not provide for ease of navigation, placement and therapy delivery from one or more devices and for safe energy delivery, especially in the context of ablation therapy for cardiac arrhythmias with epicardial catheter devices.
Thus, there is a need for devices that can effectively deliver electroporation ablation therapy selectively to tissue in regions of interest while minimizing damage to healthy tissue. In particular, there is a need for devices that can efficiently deliver electroporation therapy to desired tissue regions while at the same time minimizing the occurrence of irreversible electroporation in undesired tissue regions. Such elective and effective electroporation delivery methods with enhanced safety of energy delivery can broaden the areas of clinical application of electroporation including therapeutic treatment of a variety of cardiac arrhythmias.